[Python-Dev] peps: document requirements

[Christian Heimes]

Am 30.09.2013 20:16, schrieb Antoine Pitrou:
> On Mon, 30 Sep 2013 17:08:00 +0200 (CEST)
> christian.heimes <python-checkins at python.org> wrote:
>> +
>> +* It should return ``0`` for zero length input. (Note: This can be handled as
>> +  special case, too.)
> 
> What is this required for? The main requirement is that equal stuff
> hashes equal, but there's no reason for zero-length input to hash to
> zero, AFAIK.

http://hg.python.org/cpython/file/d7ba4ca59023/Objects/object.c#l852

    We make the hash of the empty string be 0, rather than using
    (prefix ^ suffix), since this slightly obfuscates the hash secret

It's not a hard requirement, hence 'should' instead of 'must' like in
all other cases.

Christian